Method for bending and laying pipe under water

ABSTRACT

The present invention relates to a method for laying pipe under water to interconnect at least two installations, such as surface or submerged facilities associated with wells, manifolds, collection facilities and the like. More particularly, it relates to a method for bending and laying pipe under water. In one embodiment, the method utilizes a submersible chamber in which workmen may operate in a dry atmosphere.

Unite States Patent [191 Moore METHOD FOR BENDING AND LAYING PIPE UNDER WATER [75] Inventor: Thomas S. Moore, Oklahoma City,

Okla.

[73] Assignee: Transworld Drilling Company,

Oklahoma City, Okla.

[22] Filed: May 24, 1971 [21] Appl. No.: 146,242

Related U.S. Application Data [63] Continuation-impart of Ser. No. 851,400, Aug. 19,

[52] U.S. Cl. 61/72.3, 166/.5 [51] Int. Cl. F161 1/00, E21b 43/01 [58] Field of Search 61/723, 72.1;

[56] References Cited UNITED STATES PATENTS Cox et al. 61/723 Aug. 28, 1973 3,431,739 3/1969 Richardson et al 61/723 3,482,410 12/1969 Roesky et al. 3,595,312 7/1971 Matthews, Jr. 61/723 Primary Examiner-Jacob Shapiro Attorney-Wil1iam G. Addison [57] ABSTRACT The present invention relates to a method for laying pipe under water to interconnect at least two installations, such as surface or submerged facilities associated with wells, manifolds, collection facilities and the like. More particularly, it relates to a method for bending and laying pipe under water. In one embodiment, the method utilizes a submersible chamber in which workmen may operate in a dry atmosphere.

9 Claims, 15 Drawing Figures Patented Aug. 28, 1973 3,754,404

5 Sheets-Sheet 1 77/0MA6' 4: 4/00/15 INVENTOR.

5 ShGBtS-ShQBt 2 77/041146 J! MOORE INVENTOR.

ATTOAIVE) Patnted Aug. 28, 1973 3,754,404

5 Sheets-Sheet 5 77/01/45 5. MOORE INVENTOR.

Patented Aug. 28, 1973 3,754,404

5 Sheets-Sheet 4 MOM/45' 5. MOO/96' INVENTOR.

ATTORNEY Patented Aug. 28, 1973 3,754,404

5 Sheets-Sheet 5 FIG. l5

METHOD FOR BENDING AND LAYING PIPE UNDER WATER This application is a continuation-in-part of my copending application, Ser. No. 851,400, filed Aug. 19, l969.

BACKGROUND OF THE INVENTION Heretofore, it has been the practice to use rigs when drilling and completing and depleting underwater wells such as oil, gas or the like in the Gulf of Mexico and in the ocean. More recently, interest has developed in drilling and completing wells at locations relatively far out from the shoreline and at relatively great depths, e.g., 200-300 feet or greater. While wells can be drilled at'such depths from floating drilling rigs, it is notpractical for divers to operate at those depths for completing and servicing the wells. Consideration has been given to using underwater vessels for conveying workmen to such depths whereby they can work in a dry atmo-' sphere.

Even with the use of such vessels, there still remains the problem of bending, laying and otherwise installing flow pipe lines from such wells to manifolds or collecting stations.

Heretofore, it has been the practice to either attach sections of pipe to buoys, float the sections out'to position and then use divers to connect the sections to the well equipment or to use a barge from'which pipe is laid in a reverse curve configuration utilizing a stinger ora tension means located on the barge. Alternatively, pipe has been dragged from the shoreline along-the floor of the body of 'water out to the well. Eachof such practices has certain drawbacks and-limitations. which" makes it less'than completely satisfactory for operation at depths greater than 200-300 feet.

SUMMARY OF THE INVENTION shore installations,

b. stringing-pipe pulling means between two installations, through said pipe bending and straightening means, l

c. connectingpipe to one end of said pipe pulling means on one of said installations,

d. connecting power means located on anotherof'the installations to the other end of the pulling means, and

e. actuating the power means to draw the pipe through the pipe bending and straightening means to interconnect said installations.

In one embodiment, the method .utilizes a submersible chamber in which workmen may operate in a'dry atmosphere, and the pipe bending and straightening means is located within the submersible chamber.

DESCRIPTION OF DRAWINGS ber, and associated equipment for stringing pipe pulling means;

FIG. 6 is a schematic, elevational view illustrating the laying and pulling of pipe in accordance with this invention;

FIGS. 7 12 are schematic, elevational views illustrating alternate methods for stringing pipe pulling means; and

FIGS. 13 15 are schematic, elevational views illustrating the laying and pulling of pipe in accordance with different embodiments of this invention.

DESCRIPTION OF PREFERRED EMBODIMENTS In accordance with the present invention, a method is provided to'interconnect at least two installations, at least one of which is located offshore. The term installation as used herein refers to those facilities associated with offshore wells such as submerged wellheads, submerged or surface platforms of offshore wells, storage tanks, distribution'manifolds and the like. When the installation is a submerged wellhead or submerged platform, it is further contemplated'that the term installation includes a surface facility such as surface platform or floating vessel whereon pipe can be readily joined to a pipe pulling meansto practice the instant invention. In accordance with a preferred method of this invention, a first surface vessel (FIG. 1) is positioned in a region above a first submerged well provided with a wellhead 12 which projects a relatively short distance above the mud line in the bottom of the body of water. A hemispherical mounting platform 14 is secured to that wellhead. A chamber 15, carried by'vessel 10, is lowered by cable 11 and mated with'platform'14. The chamber has a water-tight compartment in its upper portion where workmen may be transported and an open bottom. After the chamber is mated with hemispherical platform 14, water is pumped from the lower compartment and replaced by air. The workmen then can descend into the lower compartment to carry on activities as more fully described hereinafter.

A buoy I6 is released from chamber 15 through an opening 18 in platform 14 and trails a messenger line 20. The line is mounted on winch 22 located in chamber 15. When the buoy reaches'the surface and vessel 10, it is disconnected and the messenger line is connected to the lead end of a pulling cable 24 carried by reel 25 on vessel 10. The messenger line and lead end of the pulling cable then are hauled down into chamber 15 through opening 18 in platform 14. The messenger line 20 is disconnected from the lead end of the pulling cable while the latter is within chamber 15.

The chamber then is raised to the surface (FIG. 2)

drawing the pulling cable after it through opening 18 in which floats on the surface. As-shownin FIG. 4, the first surface vessel 10 and chamber l5,are moved to a location in'a region above a second well provided with a wellhead 28 to which is secured a hemispherical platform 30. Chamber l5is lowered by cable 11 into a mating position with platform 30. Buoy 32 is ejected from chamber 15 carrying a messenger line 20 through a water-tight opening 34 provided in the side wall of chamber 15.

At the surface, the buoy is disconnected and the messenger line is connected to the lead end of a pulling cable 24 carried by reel 25 on vessel 10. The line and cable then are hauled down into chamber 15 through opening 34. As shown in FIG. 5, after the messenger line is disconnected from the lead end 35 of the pulling cable while it is inside chamber 15, a buoy 36 is ejected to the surface trailing the lead end 35 through opening 40 in platform 30. At the surface, buoy 36 is disconnected from lead end 35 of pulling cable 24 and the lead end 35 then is connected to the end of the pulling cable connected to buoy 26 strung through the equipment associated with the first wellhead 12.

It will be evident that once the lead ends of these pulling cables have been joined and the buoys removed, the resulting integral cable will drop to the ocean floor and that such cable will interconnect vessel 10, the two platforms and pulling vessel 27.

As shown in FIG. 6, a winch 42 mounted on pulling vessel 27 is activated to haul the joined pulling cables from the reel 25 located on vessel through openings 34 in chamber 15, 40 in platform 30, 18 in platform 14, and onto pulling vessel 27.

Pipe is connected to the trailing end of the pulling cable on vessel 10. The pipe may be either in a continuous length carried in a coil on that vessel or it may be in convenient lengths of straight pipe which are welded or otherwise secured together into long lengths, as used. 7

As further illustrated in FIG. 6, the pipe 44 is pulled through bending rollers 46 and straightening rollers 40 located in chamber and platform 30, respectively. It will be understood, of course, that both sets of rollers could be located within the chamber itself or within the platform. It is desirable that both sets of rollers be positioned in such a manner that, when in operation, they are in a dry atmosphere where they can be readily serviced and inspected. Further, it is desirable to have the rollers power operated to facilitate passage of thepipe therethrough.

The lead end of pipe 44 is passed through the bending and straightening rollers whereby the desired angle is imparted thereto. Winch 42 on pulling vessel 27 continuously hauls the pulling cable along, pulling the lead end of pipe 44 onwardly into opening 18 in platform 14.

Thereafter, a wire line knife (not shown) is lowered to platform 14 and actuated to sever the trailing end of the pulling cable from the lead end of the pipe.

The portion of pipe within chamber 15 and platform 30 is severed by workmen located therein and then connected to wellhead 28 within that platform. That portion of pipe extending downwardly into the water from vessel 10 to chamber 15 then is raised back on board vessel 10 for later use. After the pipe has been connected to wellhead at this well, the chamber is moved over to platform 14 to permit workmen, operating in a dry atmosphere, to connect the lead end of the pipe to that platform.

While the invention has been illustrated and described with respect to a method of bending and laying pipe to interconnect two wells, it will be understood, of course, that it is equally applicable with respect to bending and laying pipe to interconnect a plurality of wells or wells with a manifold or collecting station. The oil production from all wells then can be transmitted to a tanker on the surface by conventional hose, pipe or like means.

It is a feature of this invention that there are several methods, in addition to the one already disclosed,

which can be employed for stringing pulling cable through the equipment associated with the second wellhead indicated by reference number 28.

Thus, in accordance with one such further embodiment (FIG. 7), after chamber 15 is mated and secured to platform 30, buoys 32 trailing messenger lines 20 are ejected to the surface through openings 34 and 40. At the surface the buoys are removed and the lines are connected to separate lengths of pulling cable 24, the lead ends of which are hauled down and joined to gether within chamber 15 (FIG. 8). Thus, in this embodiment the trailing portion of the pulling cable passing through opening 34 is held on vessel 10 while its lead end is joined, within chamber 15, to the lead end of pulling cable passing through opening 40 in platform 30. The trailing end of the latter cable then is removed from vessel 10 and connected to the end of the pulling cable 24 secured to buoy 26 strung through the equipment associated with the first wellhead 12.

In accordance with another embodiment of the invention (FIG. 9) for stringing pulling cable at the second wellhead 28, chamber 15 again is mated with platform 30. A buoy 32 is ejected to the surface trailing a messenger line 20 through opening 40 in the platform. That line is connected to a pulling cable 24 and the lead end thereof is hauled down and into chamber 15 through opening 40. Thereafter, the chamber is raised to the surface (FIG. 10) hauling the pulling cable 24 after it, whereupon the lead end then is passed through opening 34 of chamber 15 and secured to vessel 10. The chamber then is lowered again to mate with platform 30. The trailing end of that portion of the pulling cable which passes through opening 40 then is connected to tne end 24 of the pulling cable secured to buoy 26 strung through the equipment associated with the first wellhead 12.

In accordance with yet another embodiment of the invention (FIG. 11) for stringing pulling cable at the second wellhead 28, chamber 15 is in a raised position near vessel 10. The lead endof pulling cable 24 carried on vessel 10 is introduced into the chamber 15 through opening 34. The pulling cable then is drawn down to the wellhead by lowering chamber 15 and mating it with platform 30 (FIG. 12). A buoy 32 then is ejected to the surface trailing a messenger line 20 through opening 40 in platform 30. At the surface, the buoy is disconnected and a second pulling cable is connected to the messenger line. The line and cable then are hauled down into the chamber, the messenger line is disconnected and the lead end of the second pulling cable is joined to the lead end of the first pulling cable within the chamber. The trailing end of the second pulling cable then is connected with the end of pulling cable 24 supported by buoy 26 strung through equipment associated with wellhead 12.

It will be seen that in accordance with each of these embodiments, once the end of the pulling cable 24 supported by buoy 26 in association with wellhead 12 is connected with the end of the pulling cable 24 associated with wellhead 28 and the buoys removed, the resulting integral pulling cable will sink to the bottom of the body of water.

While the invention has been described in connection with the utilization of water-tight chamber to provide a method for laying pipe in relatively deep water, for example, at depths greater than 200 feet, it will be understood, of course, that it can be employed in relatively shallow water, namely that in which divers can operate. In such a modification, the bending and straightening rollers need only be mounted on a frame associated with the wellheads.

It is possible, if the wellheads are relatively close together, for example one-half mile or less, to employ just one vessel, the only limitation being the diameter of the pipe to be bent and laid. In general, pipe of 8% inches 0D. or less may be readily handled in accordance with this invention.

According to the embodiment depicted in FIG. 13, a pulling cable 24 is strung from offshore installation 52 through pipe bending and straightening means 50 to winch 54 located on the shore. In stringing pulling cable 24, its lead end first is threaded through the pipe bending and straightening means 50 and then may be passed to a boat, barge or the like for transfer to winch 54. Pipe is connected to the trailing end of pulling cable 24 on installation 52. The pipe may be either in a continuous length carried in a coil on that installation or it may be in convenient lengths of straight pipe which are welded or otherwise secured together into long lengths as used. Winch 54 is actuated to draw pulling cable 24 and pipe 44 from installation 52 through pipe bending and straightening means 50 to the shore. One end of the pipe is then connected to the surface platform of installation 52 or, if desired, to submerged wellhead 28 and the other end connected to the shore installation such as, for example, a collection tank (not shown) to thereby interconnect the two.

FIG. 14 depicts an embodiment wherein a wellhead 28 located in relatively deep water is interconnected with a shore installation provided with a winch 54 in accordance with the method of the instant invention. Pulling cable 24 is strung from vessel 10 through pipe bending and straightening means 50 and on to winch 54 located on the shore. In stringing pulling cable 24, a submersible chamber having a structure as described hereinbefore may be used. In using the chamber, the lead end of the pulling cable is passed through opening 34 into the chamber and the latter then is lowered by cable 11 into mating position with platform 30 of wellhead 28. the lead end of the cable then is passed through bending and straightening means 50 and then through opening 40. It may be passed to the surface by attaching it to a buoy. The lead end then may be transported to winch 54 by a boat, barge or the like. Pipe is connected to the trailing end of the pulling cable on vessel 10. Winch 54 is actuated to haul the joined cable 24 and pipe 44 from vessel 10 through cable bending and straightening means 50 to the shore. The end of the pipe on the shore then is connected to the shore installation which may be, for example, storage tanks, manifolds or the like (not shown). Thereafter, pipe 44 is severed and connected to wellhead 28. That portion of pipe 44 extendingdownwardly into the water from vessel 10 then is raised back on board vessel 10 for later use.

FIG. 15 depicts an embodiment wherein the surface platforms of the two offshore installations 52'are interconnected in accordance with the method of the instant invention. Submerged pipe bending and straightening means 50 are provided near the mud line of each of'the offshore installations 52. Pipe pulling cable 24 is 6 passed from the one installation 52 through the two pipe bending and straightening means 50 and connected to winch 54 located on the other installation.

Pipe is connected to the trailing end of the pulling cable and winch 54 is actuated to draw the pulling cable and the pipe from the one installation through both pipe bending and straightening means 50 to the other installation to thereby interconnect the two.

If installation 52, illustrated in FIGS. 13 and 14, is an appreciable distance offshore, it may be desirable to utilize a pulling vessel to pull the pipe within range of winch 54. Further, if the offshore installations illustrated in FIG. 15 are widely spaced, a pulling vessel may be utilized to pull the pipe near the second installation for introduction through the pipe bending and straightening means associated with that installation.

While the present invention has been described with respect to certain preferred embodiments thereof, it will be understood, of course, that certain changes, modifications, and substitutions may be made therein without departing from its true scope as defined by the I appended claims.

What is claimed is:

l. A method for bending and laying pipe under water to interconnect at least two installations, at least one of which is located offshore, comprising:

a. providing submerged pipe bending and straightening means near the mud line of at least one of the offshore installations,

b. stringing pipe pulling means between two installations,-through said pipe bending and straightening means,

c. connecting pipe to one end of said pipe pulling means at one of said installations,

d. connecting power means, located at anotherof the installations, to the other end of said pipe pulling means,

e. actuating said power means to pull said pipe pulling means and trailing pipe from said one installation, through said pipe bending and straightening means and onto said other installation,

f. disconnecting said pipe pulling means from said pipe at said other installation and connecting the pipe to that installation, and

g. connecting the other end of said pipe to said one installation to thereby interconnect said installations.

2. The method of claim 1 wherein said pipe is pulled from an offshore installation having a surface platform onto a shore installation upon which the power means is located.

3. The method of claim 1 wherein the pipe is pulled from anoffshore installation comprising a submerged wellhead, through pipe bending and straightening means located in a chamber mated with the wellhead and onto a shore installation upon which the power means is located. I

4. The method of claim 1 wherein said 'pipe is pulled between offshore installations having surface platforms and through pipe bending and straightening means located near the mud line of each of said installations.

5. A method for bending and laying pipe under water to interconnect first and second submerged platforms which comprises:

a. stringing pipe pulling means between spaced apart first and second surface vessels and through the submerged platforms,

b. connecting pipe to one end of said pulling means on said first vessel,

c. actuating power means on said second vessel to pull said pipe from said first vessel down to the second platform,

d. bending the pipe at said second platform while continuing to actuate the power means to pull the pipe toward the first platform,

e. disconnecting said pulling means from said pipe at the first platform,

f. connecting said pipe to the first platform, and

g. severing said pipe at said second platform and connecting it thereto, whereby to connect said platforms with said pipe.

6. The method as set forth in claim in which said pipe pulling means comprises cable which is strung between the surface vessels and platforms by:

a. positioning said first surface vessel in a region over said first platform and lowering a chamber to and mating it with said platform,

b. releasing a buoy trailing a messenger line upwardly to the first vessel through an opening in the platform,

c. connecting a pulling cable located on said first vessel to the messenger line and pulling both the line and the lead end of the cable down into the chamber through the opening in the platform,

d. returning the lead end of the cable to the surface by raising the chamber to the surface and then connecting said lead end to said power means on said second surface vessel and transferring the other end to floating means on the surface,

e. positioning the first surface vessel in a region above the second platform and lowering a chamber to and mating it with that platform,

f. releasing a buoy trailing a messenger line upwardly through an opening in said chamber,

g. connecting a pulling cable located on said first vessel to the messenger line and pulling both that line and the lead end of the cable down into the chamber,

h. releasing a buoy trailing the lead end of the pulling cable to the surface through an opening in said second platform and thereafter,

i. connecting the lead end of that pulling cable to the floating end of the pulling cable strung through the first platform.

7. The method as set forth in claim 5 in which said pipe pulling means comprises cable which is strung between the surface vessels and platforms by:

0. connecting a pulling cable located on said first vesf. releasing to the first vessel a buoy trailing a messenger line through an opening in the chamber and another buoy and a messenger line through an opening in the platform,

g. attaching pulling cable located on the first vessel to each messenger line and hauling the lines and lead ends of the cable into the chamber,

h. joining the lead ends of the pulling cables together while they are in the chamber, and

i. connecting the other end of the pulling cable passing through the opening in the platform to the floating end of the pulling cable strung through the first platform.

8. The method as set forth in claim 5 in which said pipe pulling means comprises cable which is strung between the surface vessels and platforms by:

a. positioning said first surface vessel in a region over said first platform and lowering a chamber to and mating it with said platform,

b. releasing a buoy trailing a messenger line upwardly to the first vessel through an opening in the platform,

c. connecting a pulling cable located on said first vessel to the messenger line and pulling both the line and the lead end of the cable down into the chamber through the opening in the platform,

d. returning the lead end of the cable to the surface by raising the chamber to the surface and then connecting said lead end to said power means on said second surface vessel and transferring the other end to floating means on the surface,

e. positioning the first surface vessel in a region above the second platform and lowering a chamber to and mating it with that platform,

f. releasing a buoy trailing a messenger line upwardly through an opening in said platform,

g. connecting a pulling cable located on said first vessel to the messenger line and hauling both the line and the lead end of the pulling cable down into the chamber through said opening in said second platform,

h. returning the lead end of the pulling cable to the surface by raising the chamber and passing said lead end outwardly through an opening in the chamber and securing it to the first vessel,

returning the chamber to its mating position with the second platform secured to said second well, and j. connecting the end of that portion of the pulling cable passing through the opening in said platform secured to the second well to the floating end of the pulling cable strung through the first platform.

9. The method as set forth in claim 5 in which said pipe pulling means comprises cable which is strung between the surface vessels and platforms by:'

a. positioning said first surface vessel in a region over said first platform and lowering a chamber therefrom to mate with said platform,

b. releasing a buoy trailing a messenger line upwardly to the first vessel through an opening in the platform,

0. connecting a pulling cable located on said first vesselto the messenger line and pulling both the line and the lead end of the cable down into the chamber through the opening in the platform,

d. returning the lead end of the cable to the surface by raising the chamber to the surface and then consecond well,

i. connecting a pulling cable located on said first vessel to the messenger line and hauling both that line and the lead end of that pulling cable down into the chamber,

j. joining the lead ends of the pulling cables together while they are in the chamber, and

k. connecting the end of that portion of that pulling cable passing through the opening in the platform secured to the second well to the floating end of the pulling cable strung through the first platform.

UNITED STATES PATENT OFFICE I QERTIFICATE OF CORRECTION Patent No. 3,754, 0 Dated August 975 Inventor(s) Thomas S. Moore It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 5, line 28, "rollers 40" should read rollers 48 (p. 6, line 18) Column 7, line 52, "is" should read it v (p. 16, line 15) Signed and sealed this 25th day of December 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. v RENE D. TEGTMEYER Attesting Officer Acting Commissioner of Patents USCOMM-DC 6O376-P6Q LLS GOVERNMENT PRINTING O FHC E: I959 0-386-334 FORM PO-1 050 (10-69) 

1. A method for bending and laying pipe under water to interconnect at least two installations, at least one of which is located offshore, comprising: a. providing submerged pipe bending and straightening means near the mud line of at least one of the offshore installations, b. stringing pipe pulling means between two installations, through said pipe bending and straightening means, c. connecting pipe to one end of said pipe pulling means at one of said installations, d. connecting power means, located at another of the installations, to the other end of said pipe pulling means, e. actuating said power means to pull said pipe pulling means and trailing pipe from said one installation, through said pipe bending and straightening means and onto said other installation, f. disconnecting said pipe pulling means from said pipe at said other installation and connecting the pipe to that installation, and g. connecting the other end of said pipe to said one installation to thereby interconnect said installations.
 2. The method of claim 1 wherein said pipe is pulled from an offshore installation having a surface Platform onto a shore installation upon which the power means is located.
 3. The method of claim 1 wherein the pipe is pulled from an offshore installation comprising a submerged wellhead, through pipe bending and straightening means located in a chamber mated with the wellhead and onto a shore installation upon which the power means is located.
 4. The method of claim 1 wherein said pipe is pulled between offshore installations having surface platforms and through pipe bending and straightening means located near the mud line of each of said installations.
 5. A method for bending and laying pipe under water to interconnect first and second submerged platforms which comprises: a. stringing pipe pulling means between spaced apart first and second surface vessels and through the submerged platforms, b. connecting pipe to one end of said pulling means on said first vessel, c. actuating power means on said second vessel to pull said pipe from said first vessel down to the second platform, d. bending the pipe at said second platform while continuing to actuate the power means to pull the pipe toward the first platform, e. disconnecting said pulling means from said pipe at the first platform, f. connecting said pipe to the first platform, and g. severing said pipe at said second platform and connecting it thereto, whereby to connect said platforms with said pipe.
 6. The method as set forth in claim 5 in which said pipe pulling means comprises cable which is strung between the surface vessels and platforms by: a. positioning said first surface vessel in a region over said first platform and lowering a chamber to and mating it with said platform, b. releasing a buoy trailing a messenger line upwardly to the first vessel through an opening in the platform, c. connecting a pulling cable located on said first vessel to the messenger line and pulling both the line and the lead end of the cable down into the chamber through the opening in the platform, d. returning the lead end of the cable to the surface by raising the chamber to the surface and then connecting said lead end to said power means on said second surface vessel and transferring the other end to floating means on the surface, e. positioning the first surface vessel in a region above the second platform and lowering a chamber to and mating it with that platform, f. releasing a buoy trailing a messenger line upwardly through an opening in said chamber, g. connecting a pulling cable located on said first vessel to the messenger line and pulling both that line and the lead end of the cable down into the chamber, h. releasing a buoy trailing the lead end of the pulling cable to the surface through an opening in said second platform and thereafter, i. connecting the lead end of that pulling cable to the floating end of the pulling cable strung through the first platform.
 7. The method as set forth in claim 5 in which said pipe pulling means comprises cable which is strung between the surface vessels and platforms by: a. positioning said first surface vessel in a region over said first platform and lowering a chamber to and mating is with said platform, b. releasing a buoy trailing a messenger line upwardly to the first vessel through an opening in the platform, c. connecting a pulling cable located on said first vessel to the messenger line and pulling both the line and the lead end of the cable down into the chamber through the opening in the platform, d. returning the lead end of the cable to the surface by raising the chamber to the surface and then connecting said lead end to said power means on said second surface vessel and transferring the other end to floating means on the surface, e. positioning the first surface vessel in a region above the second platform and lowering a chamber to and mating it with that platform, f. releasing to the first vessel a buoy trailing a messenger line through an oPening in the chamber and another buoy and a messenger line through an opening in the platform, g. attaching pulling cable located on the first vessel to each messenger line and hauling the lines and lead ends of the cable into the chamber, h. joining the lead ends of the pulling cables together while they are in the chamber, and i. connecting the other end of the pulling cable passing through the opening in the platform to the floating end of the pulling cable strung through the first platform.
 8. The method as set forth in claim 5 in which said pipe pulling means comprises cable which is strung between the surface vessels and platforms by: a. positioning said first surface vessel in a region over said first platform and lowering a chamber to and mating it with said platform, b. releasing a buoy trailing a messenger line upwardly to the first vessel through an opening in the platform, c. connecting a pulling cable located on said first vessel to the messenger line and pulling both the line and the lead end of the cable down into the chamber through the opening in the platform, d. returning the lead end of the cable to the surface by raising the chamber to the surface and then connecting said lead end to said power means on said second surface vessel and transferring the other end to floating means on the surface, e. positioning the first surface vessel in a region above the second platform and lowering a chamber to and mating it with that platform, f. releasing a buoy trailing a messenger line upwardly through an opening in said platform, g. connecting a pulling cable located on said first vessel to the messenger line and hauling both the line and the lead end of the pulling cable down into the chamber through said opening in said second platform, h. returning the lead end of the pulling cable to the surface by raising the chamber and passing said lead end outwardly through an opening in the chamber and securing it to the first vessel, i. returning the chamber to its mating position with the second platform secured to said second well, and j. connecting the end of that portion of the pulling cable passing through the opening in said platform secured to the second well to the floating end of the pulling cable strung through the first platform.
 9. The method as set forth in claim 5 in which said pipe pulling means comprises cable which is strung between the surface vessels and platforms by: a. positioning said first surface vessel in a region over said first platform and lowering a chamber therefrom to mate with said platform, b. releasing a buoy trailing a messenger line upwardly to the first vessel through an opening in the platform, c. connecting a pulling cable located on said first vessel to the messenger line and pulling both the line and the lead end of the cable down into the chamber through the opening in the platform, d. returning the lead end of the cable to the surface by raising the chamber to the surface and then connecting said lead end to said power means on said second surface vessel and transferring the other end to floating means on the surface, e. positioning the first surface vessel in a region above the second platform while keeping the chamber in a raised position, f. introducing the lead end of a pulling cable into the chamber through an opening in the chamber wall, g. lowering the chamber to and mating it with the platform secured to the second well, h. releasing a buoy trailing a messenger line upwardly through an opening in the platform secured to said second well, i. connecting a pulling cable located on said first vessel to the messenger line and hauling both that line and the lead end of that pulling cable down into the chamber, j. joining the lead ends of the pulling cables together while they are in the chamber, and k. connecting the end of that portion of that pulling cable passing through the opening in the platform seCured to the second well to the floating end of the pulling cable strung through the first platform. 